I too am somewhat disappointed in Ayu's 20th anniversary celebrations thus far, but who knows what she has planned? She seems to do everything last minute haha.
ALSO: There's an artist called Rina Sawayama, she's a London based artist who recently released her first ep called RINA. She's highly influenced by late 90s/early 2000s jpop. One track in particular, Alterlife, sounds (structurally, melodically and lyrically) like Ayu during that time period...I recommend everyone listen to it + RINA as a whole. It's not j-pop (all tracks are sung in English), but it is certainly influenced by it!!!
Alterlife PV:
https://www.youtube.com/watch?v=Nhf9gkkYaBg